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COLUMBUS — In the spring, Michigan coach Jim Harbaugh had a big request for Mike Sainristil: become a defensive back.

Heading into his fourth year as a Wolverine, Sainristil had always played receiver at the college level. He’d proven his ability to make blocks, reel in difficult passes and make a positive impact on the offense overall.

But as much as Sainristil could do on offense, Harbaugh believed the Michigan defense needed him more.

“Figured it was gonna be tough to replace (defensive back) Dax Hill, and just felt like Mikey had the skill set for it,” Harbaugh said Saturday. “And he was smart enough to be able to do that.”

Saturday, in the biggest game of the third-ranked Wolverines’ season — and perhaps the biggest game the program has had in years — Sainristil epitomized his journey in a single afternoon. By the end of Michigan’s 45-23 win over No. 2 Ohio State, he proved Harbaugh right, and proved any doubter wrong.

But not right away.

The Buckeyes targeted Sainristil on their first drive of the game. He was the link in the Wolverines’ armor that Ohio State thought to be weakest. At first, the Buckeyes appeared to be right. On a crossing route in the endzone, receiver Emeka Egbuka found himself multiple steps in front of Sainristil, giving Ohio State an early 7-0 lead.

But, it was par for the course for Sainristil.

“Definitely,” Sainristil said Saturday when asked if he knew he’d be targeted. “With the way Emeka Egbuka has been playing this year, we knew that was a guy that they wanted to get the ball to in certain situations.”

But it’s not just Egbuka; Sainristil has found himself a target for opposing offenses on multiple occasions this season. Standing at 5-foot-10 and 182 lbs, Sainristil isn’t a big body, and he can struggle to match up against tight ends and bigger receivers coming over the middle. It’s nothing he isn’t aware of himself.

“I won’t be surprised if I’m starting to get attacked again,” Sainristil said Nov. 1. “Just with the opponents we have coming up. But like I said, I’m just going to make sure that I do my job.”

His size, paired with his lack of experience prior to this season at defensive back, puts Sainristil at a disadvantage. It’s been part of his journey.

Since fall camp, Sainristil has embraced this. It’s not the situation he wants to be in, but it’s been his reality.

“Games are gonna go along and I’m gonna be put in different situations I’ve never been in simply because I’m on a new side of the ball,” Sainristil said Aug. 23. “So will I ever be 100% comfortable this year? Who’s to say. But you know, I’m gonna play to my best ability at all times.”

He’s fought through those growing pains, succeeding in coverage at times, getting blatantly outplayed on others. He’s found himself in the backfield being muscled out of the play, and then hitting home on blitzes in the same day.

It’s been a take-a-punch, return-a-punch year for Sainristil, each wound teaching him a lesson and powering up his next strike.

Early Saturday, Egbuka and the Buckeyes put Sainristil through the ringer. But by the end of the day, Sainristil delivered the knockout punch.

With Ohio State down 31-20 and driving, a touchdown would’ve brought the game within one score and revitalized the scarlet and gray in Columbus. Sainristil lined up against tight end Cade Stover in the red zone. Stover, just like Egbuka did before, ran a crossing route, getting multiple steps on Sainristil.

This time, though, Sainristil made the play.

Activating a second gear, Sainristil closed ground on Stover, extending his hand through the Buckeye tight end’s hands and knocking the ball loose, resulting in an incomplete pass.

“The only thing running through my head at that time was, ‘Just don’t give up another touchdown. Strain to the ball and get it out any way you can,’ ” Sainristil said. “… And I saw the ball go into the tight end’s hands and the only thing I was thinking was just ‘Punch it out and just don’t give up that touchdown.’ ”

Thanks to Sainristil, Michigan forced a field goal. On the very next play, sophomore running back Donovan Edwards ripped off a 75-yard touchdown, effectively putting the game out of reach. Edwards, though, put the credit in Sainristil’s hands.

“What really kind of helped us out and saved the day was Mikey,” Edwards said. “… That’s basically all it is right there — coming up big in big situations.”

As the clock struck double zeroes, Sainristil’s joy radiated in a display of pride for all of Ohio Stadium and the world to see — sprinting to midfield with a Michigan flag in hand, planting it into the block ‘O’.

Saturday, Columbus belonged to the Wolverines. And Sainristil, sitting atop the list of contributors to that claim — after all the pride and pains of switching positions — was the one to declare it.